Open Access
Delay-throughput curves for timer-based OBS burstifiers with light load
(IEEE, 2006) Izal Azcárate, Mikel; Aracil Rico, Javier; Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
The OBS burstifier delay-throughput curves are analyzed in this paper. The burstifier incorporates a timer-based scheme with minimum burst size, i. e., bursts are subject to padding in light-load scenarios. Precisely, due to this padding effect, the burstifier normalized throughput may not be equal to unity. Conversely, in a high-load scenario, padding will seldom occur. For the interesting light-load scenario, the throughput delay curves are derived and the obtained results are assessed against those obtained by trace-driven simulation. The influence of long-range dependence and instantaneous variability is analyzed to conclude that there is a threshold timeout value that makes the throughput curves flatten out to unity. This result motivates the introduction of adaptive burstification algorithms, that provide a timeout value that minimizes delay, yet keeping the throughput very close to unity. The dependence of such optimum timeout value with traffic long-range dependence and instantaneous burstiness is discussed. Finally, three different adaptive timeout algorithms are proposed, that tradeoff complexity versus accuracy.
Open Access
Resolución de alias para el cálculo de topologías
(2007) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
The network topology is a fundamental parameter for managers and researchers. The traditional methodology for discovering the topology of a network is based on the tool traceroute, used from several vantage points in different subnetworks. The result is a set of sink trees where the nodes are the discovered IP addresses from the routers. However, few tools have faced the problem of identifying the nodes in different sink trees as interfaces in the same router. This paper shows a new methodology for this problem of alias resolution. It has been used in the european research network using the ETOMIC platform. It shows that the traditional methodologies are not effective in today’s networking scenario but can be easily improved at least in a factor of 3 in the number of successes.
Open Access
On linear prediction of Internet traffic for packet and burst switching networks
(IEEE, 2001) Morató Osés, Daniel; Aracil Rico, Javier; Díez Marca, L. A.; Izal Azcárate, Mikel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
In this paper, we show that prediction algorithms in the least mean square error sense prove better in a burst rather than in a packet switching network. For the latter, further information about the packet arrival distribution within the prediction interval is required. Regarding burst switching, we compare Optical Burst Switching networks with and without linear prediction to conclude that linear prediction provides a significant improvement in end-to-end latency with low bandwidth waste.
Open Access
Multiresolution analysis of optical burst switching traffic
(IEEE, 2003) Aracil Rico, Javier; Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
In this paper, a Multiresolution Analysis is conducted in order to study the self-similar features of Optical Burst Switching (OBS) traffi c. The scenario consists of an OBS backbone with input traffic from a large number of Internet users, that generate Poisson-arriving heavytailed bursts. The results show that long-range dependence is preserved at timescales longer than the burst assembly timeout value while the traffic variability at short timescales is increased.
Open Access
IP addresses distribution in Internet and its application on reduction methods for IP alias resolution
(IEEE, 2009) García-Jiménez, Santiago; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
Discovery of Internet topology is an important and open task. It is difficulted by the high number of networks and internetworking equipments, and even by the dynamic of those interconnections. Mapping Internet at router-level needs to identify IP addresses that belong to the same router. This is called IP address alias resolution and classical methods in the state of the art like Ally need to test IP addresses in pairs. This means a very high cost in traffic generated and time consumption, specially with an increasing topology size. Some methods have been proposed to reduce the number of pairs of IP addresses to compare based on the TTL or IP identifier fields from the IP header. However both need extra traffic and they have problems with the probing distribution between several probing nodes. This paper proposes to use the peculiar distribution of IP addresses in Internet Autonomous Systems in order to reduce the number of IP addresses to compare. The difference between pairs of IP addresses is used to know a priori if they are candidates to be alias with certain probability. Performance evaluation has been made using Planetlab and Etomic measurement platforms. The paper justifies the reduction method, obtaining high reduction ratios without injecting extra traffic in the network and with the possibility to distribute the process for alias resolution.
Open Access
Herramienta de gestión en tiempo real de redes de área extensa
(1998) Magaña Lizarrondo, Eduardo; Aracil Rico, Javier; Villadangos Alonso, Jesús; Automática y Computación; Automatika eta Konputazioa
This paper presents PROMIS, a new network management tool based on a distributed architecture of traffic probes. It allows network managers to monitor traffic from any wide area network segment in real time using a WWW console or a Tcl/Tk graphic interface.
Open Access
Video over OBS Networks
(2008) Espina Antolín, Félix; Morató Osés, Daniel; Izal Azcárate, Mikel; Magaña Lizarrondo, Eduardo; Automática y Computación; Automatika eta Konputazioa
Open Access
Approximations for end-to-end delay analysis in OBS networks with light load
(IEEE, 2004) Morató Osés, Daniel; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Automática y Computación; Automatika eta Konputazioa
In this paper we provide an analysis of end-to-end delay in OBS networks and a large deviations approximation. The analysis is based on an exponential approximation of the OBS router blocking time and on the assumption of Poisson arrivals in routers along the path from source to destination. On the other hand, a lightload assumption is performed, namely, waiting time is mainly due to residual life of the output wavelengths and not to buffering.
Open Access
Router scheduling configuration based on the maximization of benefit and carried best effort traffic
(Kluwer Academic Publishers, 2003) Magaña Lizarrondo, Eduardo; Morató Osés, Daniel; Varaiya, Pravin; Automática y Computación; Automatika eta Konputazioa
This paper shows a configuration scheme for networks with WFQ schedulers. It guarantees maximum revenue for the service provider in the worst case of network congestion. We focus on best effort traffic and select those flows that maximize the benefit while keeping the network utilization high. We show that optimum network configuration is feasible based only on knowledge of the topology. Its dependence on the pricing scheme can be reduced and even eliminated. We offer a formulation that reaches a tradeoff between network utilization, fairness, and user satisfaction.
Open Access
Detección de congestión en la Internet europea
(IEEE, 2007) Hernández, Ana; Magaña Lizarrondo, Eduardo; Izal Azcárate, Mikel; Morató Osés, Daniel; Automática y Computación; Automatika eta Konputazioa
In this paper we present a study about the utilization of one-way delay measurements to detect and characterize network congestion in the european Internet. The experiments have been made using the ETOMIC platfom that allows one-way delay measurement with high precision timestamps. We have found a peculiar router behaviour in which the bottleneck is not the available bandwidth but it is the packet processing power of the router (backplane and CPU constraints). This router has been characterized with several network parameters. Some of them are the dependency of this limitation with the input data rate in packets per second, the size of burst packet losses measured in packets or time and the absence of specific scheduling algorithms in the router that could affect to larger flows.